Went to Christchurch a year ago, beautiful public gardens and museum, but sad to see the state of the city after the earthquakes. Like a war zone. They have low volume toilets so I didn't get to experience the opposite rotation thing. Mt Cook was amazing if you're into alpinism/hiking at all, and there are a couple beautiful lakes on the drive there from chch. If you can by any means possible get to the fiordlands that sounds like the place to be. Have fun, it's a 13 hour flight from San Fran to Auckland.